1. Field of the Invention
The present invention relates to a lifting column, preferably for height-adjustable tables, and a drive unit for lifting columns, just as the invention relates to a height-adjustable table.
2. The Prior Art
A lifting column is a synchronous lifting column, i.e., the second and third member are synchronously displaced; when the third member is displaced a distance upwards or downwards, the second member is likewise displaced a distance upwards or downwards. This is achieved in that the second member is guided in that the second member is connected to a spindle nut, which co-operates with the first spindle. This type of lifting column is, e.g., known from FIGS. 1, 3 and 6a-6b of EP 1 621 055 B1 Linak A/S. In this structure the third member of the guide is secured with its upper end to the underside of the housing by means of welding. The forces are thus led through the first spindle via the spindle nut thereon to the second spindle. From the spindle nut on the second spindle the forces are led to the third member of the guide and from there to the underside of the housing. The connection from the spindle nut on the second spindle to the third member of the guide should thus be dimensioned to be able to transfer these forces. In case of a bias the connection should also be able to withstand a torque load. This again has a negative influence on the mutual telescopic movement of the members, as the torque load is transferred to the guide. Further, it puts stress on the bottom of the housing to which the third member is secured.
The purpose of the invention is to provide a solution, which counters the above disadvantages.